The blue brothers

It isn't their best work, but two of Hollywood's leading actors do impressive impersonations of director David Ayer.

Reflecting on Ayer's no-nonsense manner on the set of the cop film End of Watch, Jake Gyllenhaal affects a gruff bark and dismissive sniff while Michael Pena adds a Sly Stallone-like, tough-guy drawl.

''He's pretty intimidating,'' Pena says of Ayer, a former US Marine and one of the most prolific writers of cop movies in Hollywood, with notches on his belt including Training Day, The Fast and the Furious, S.W.A.T. and, more recently, Street Kings, which he directed.

Ayer, who would surely be a Hollywood story if he wasn't writing and directing them, spent six months ''bullying, pleading [with], yelling [at] … and threatening'' Gyllenhaal (Source Code, Zodiac) and Pena (Million Dollar Baby) to get the performances he was seeking from the pair as police officers in End of Watch, a cop film that just might be one of the best of the genre in the past decade.

''I finally got it right,'' Ayer says, referring to his stretch of at least seven films focusing on the Los Angeles Police Department.

He admits he was reticent to make another LAPD-themed film for fear of being typecast but with the chance to direct, and Gyllenhaal on board early as both actor and an executive producer of the modest-budget (between $7 million and $10 million) film, End of Watch represented Ayer's best chance to tell ''truths'' about cops' lives. ''I'm glad I didn't go off and make a rom-com or something,'' says the self-confessed lone wolf, raised on the uncompromising streets of south central LA, where he endured a ''miserable childhood - shitty, bad''.

Yet as a ''bromance'', Ayer concedes, End of Watch has more in common with relationship tales than it has with traditional crime films or even buddy-cop movies, despite its clattering violence and raw street swagger.

The film follows two young uniformed officers, Brian Taylor (Gyllenhaal) and his partner Mike Zavala (Pena), on their beat through LA's desperate southern neighbourhoods. Their friendship is forged amid moments of bravery and reinforced daily by feisty exchanges of dialogue, often humorous, sometimes intimate.

Their brotherly concern for each other is put to the ultimate test when they are targeted by a cartel that runs drugs, humans and weapons.

''The movie is about their friendship,'' Ayer says. ''And so, unbelievably realistic chemistry was the only thing that was going to make the movie work. They had to be brothers.''

To achieve that for the 22-day shoot, Ayer put Gyllenhaal and Pena through a five-month boot camp, where the actors rode along with real law-enforcement officers to crime scenes including murders, shootings, domestic assault and drug busts, did intense weapons training with live ammunition and spent long hours together.

''They are both professional actors and they are both very good at what they do and they both showed up with that attitude,'' Ayer says. ''But I didn't want professional actors doing their craft, I wanted best friends.''

Pena, who grew up in one of Chicago's toughest neighbourhoods, admits the director's insistence he and Gyllenhaal become real-life BFFs felt like a stretch at first. ''Instantaneously, we didn't get along perfectly. It was weird, man, hanging around this guy knowing you have to be his brother from another mother.

''It was a bit easier for Jake. He's more open … and he helped me.''

Gyllenhaal says encountering the harrowing scenes the pair observed in preparing for the roles ensured they formed a close bond: ''You share something in those moments. You have to support each other.''

The film moves at a frantic pace: some of the action scenes and much of the police partners' banter is shot in a pseudo-documentary style, captured, in part, by a mini camera employed by Gyllenhaal's character as part of the story - a perhaps too-convenient plot line.

There is the requisite smattering of unthinkably inhumane criminal acts and conspicuous police bravery - End of Watch pushes some familiar buttons - but, fortunately, it doesn't tumble easily into sanctimony or endless buddy-cop cliches, a testament to Ayer's devotion to the compelling realism of the films that inspired him, such as Serpico, Taxi Driver and Mean Streets.

''Now everything is very heightened [in movies], designed and has a flashy feel, so we have lost some of the emotional honesty and the rawness,'' he says. ''I find mysteries of the human heart much more interesting than CG [computer-generated] monster-ism.''

Ayer is now shooting Breacher with Arnold Schwarzenegger and Sam Worthington (''I've told him about that accent,'' he says, gruffly).

Five of the best cop flicks

Maybe Al Pacino's greatest performance as he plays a bohemian New York cop battling a corrupt system. The complexity of flawed characters is evoked magnificently by director by Sidney Lumet.

COLORS (1988)

One of Hollywood's first and best explorations of Los Angeles gang culture, starring Sean Penn and Robert Duvall. Dated? A little. Gripping? Always. Dennis Hopper directed.

THE FRENCH CONNECTION (1971)

New York cops trace incoming drugs to European suppliers. The film bends rules and conventions. Gene Hackman is superlative as detective ''Popeye'' Doyle: an especially nasty man doing the good work of the city.

LA CONFIDENTIAL (1997)

Hard to find fault with Curtis Hanson's neo-noir take on author James Ellroy's novel about LA's criminal world and the conflicted cops who tried to manage it. Brilliant performances from our Guy Pearce and Russell Crowe.

BULLITT (1968)

Yep, there is one of the greatest ever car chases in Bullitt. But it is Steve McQueen's ''ahead of his time'' performance as a detective trying to crack a case despite political opposition that is the most rewarding part of the film. McQueen's character, Frank Bullitt, was the prototype for gritty coppers for decades to come.